The present invention relates to an imaging device and a method of manufacturing the same. In particular, the present invention is preferably applicable to an imaging device having a waveguide and a method of manufacturing such an imaging device.
In a semiconductor device, generally, in order to prevent external moisture from entering the inside of a chip, seal rings are so formed as to continuously enclose the chip from circumference. The seal rings are formed together with a plug for the chip and wirings or the like. Being stacked sequentially, eventually, the seal rings are built like a wall continuously enclosing the chip.
As one type of semiconductor devices, there is known an imaging device having a CMOS (Complementary Metal Oxide Semiconductor) image sensor. Such an imaging device is adapted to an electronic still camera, a smart phone, etc. In the imaging device, there are arranged a pixel region where pixel elements such as a photodiode converting incident light into an electric charge are formed and a peripheral circuit region where a peripheral circuit processing the electric charge converted by the pixel element as an electric signal is formed. The seal ring is so formed as to enclose the pixel region and the peripheral circuit region.
In recent years, to cope with downsizing of an electronic still camera etc., smaller-size pixel elements have been increasingly demanded for the imaging device. For this reason, in order to allow light to enter efficiently, there is proposed an imaging device in which a waveguide leading the light to a photodiode is provided. The waveguide is formed when a hole is formed by subjecting etching treatment to insulating films including an interlayer film etc. covering the pixel region and filling the hole with a predetermined gap fill member.
There is Patent Document 1 as an example of a document in which a semiconductor device having a seal ring is disclosed. Moreover, there are Patent Documents 2 and 3 as examples of documents in which an imaging device having a waveguide is disclosed.    [Patent Document 1]    Japanese Unexamined Patent Publication No. 2004-79596    [Patent Document 2]    Japanese Unexamined Patent Publication No. 2006-351759    [Patent Document 3]    Japanese Unexamined Patent Publication No. 2006-310825